The one on Ebay for ?20 is a resister.Have look near your fuel pump on the gearbox end of the head.Where the fuel pipe runs from the fuel filter there will be a fuel temp. sender in the fuel line.Unplug this and bridge the two wires with a 150ohm+ resister(these cost tops 10p from Maplins).This now tells the ECU the fuel is cold and opens the injectors for longer,so more fuel more BHP,but fuel use doesn`t seem to get worse but better.This doesn`t put any faults in the ECU and my van is still running spot on if not better.Thats what you get and i`m just telling you what it does,if you do try it i`m not responsible for any damage!!!!!